In a lithography process in manufacturing a semiconductor device, to form a fine pattern, a mask (a reticle) having size four times as large as that of a pattern to be actually formed and an exposure apparatus including a reduction projection optical system are used.
However, in recent years, according to the microminiaturization of patterns, it is becoming difficult to form a mask pattern even if the quadruple-sized mask is used. Because of design of an optical system and physical limitations of members, a reduction in the size of a pattern that can be formed on a wafer is near a limit. As resolution enhancement techniques against such problems, new exposure techniques such as double patterning are proposed. It is not easy to adopt the double patterning because there are a large number of problems such as a shift that occurs when first exposure and second exposure are superimposed. Therefore, there is a demand for a technique that can easily form various fine patterns.